Today is Equal Pay Day. It's not a celebration like Mother's Day or Independence Day or Labor Day, at least for half the US population. Instead April 12th symbolizes how far into 2011 women must work to earn what men earned in 2010 - it's not an exact date because the 2010 earnings data has not yet been released.

If you take a look at the US labor statistics for 2009 the difference between the median full-time weekly earnings of women and men are striking: women earned $687 per week while men earned $873 per week. There's a disparity no matter what level of education the employee attained: women with only a high school diploma earned 75.7% of what men earned ($542 vs $716), while earnings of women with a doctoral degree was only 70.9% that of their male counterparts ($1243 vs $1754). (fcs has the numbers in pretty graph form)

The reasons for wage disparity are complicated. Part of it has to do with many traditionally male-dominated professions paying better than female-dominated professions. Part of it has to do with some women taking time off from their careers to have children or "choosing" to spend their time doing housework or childcare rather than spending long hours in the lab or office. But that's not the whole story.

Just last week an article in Inside Higher Ed reported a study that showed that all things being equal (other than gender), women faculty members still get paid less than their male colleagues. The bottom line, according to the article:

The gender gap in faculty pay cannot be explained completely by the long careers of male faculty members, the relative productivity of faculty members, or where male and female faculty members tend to work -- even if those and other factors are part of the picture, according to research being released this week at the annual meeting of the American Education Research Association.

When all such factors are accounted for, women earn on average 6.9 percent less than do men in similar situations in higher education, says the paper, by Laura Meyers, a doctoral candidate at the University of Washington.

That difference is smaller than the overall wage gap, but still significant, especially considered over the course of a career.

It's not just a problem in academia. WhizBANG! has posted about a study that showed similar results for starting salaries of newly trained physicians.

And as an AAUW report - "Behind the Pay Gap" (pdf) - points out, there's even a pay gap in professions dominated by women. It's just smaller. Women in education earn 95% as much as men, woo hoo! Their conclusion:

Women and men who received bachelor’s degrees in 1999–2000 attended similar kinds of colleges. Women earned slightly higher grades, on average, and in other respects appear to be men’s equals in the classroom. Most women entered full-time employment following graduation. One year later, women earn only 80 percent as much as their male colleagues earn—about the same as the pay gap for the workforce as a whole. Gender segregation in undergraduate majorsand the subsequent segregation of the work force partly explain the pay gap. Yet the pay gap within fields of study and occupations suggests that the answer is not so simple. Indeed, after accounting for all factors known to affect wages, about one-quarter of the gap remains unexplained and may be attributed to discrimination.

There's not a lot that women can do about sexist employers, especially if their biases aren't overtly expressed. But salary negotiations are under our control, right? As the helpful mainsplainers who usually pop into these discussions usually point out: if women want better pay, why don't they just ask for more?

It's not necessarily that simple.

For one thing, a number of studies have shown that women expect lower pay then men. A recently published study by Melissa Williams of the Stanford School of Business and her colleagues suggest that this may be due at least in part to unconscious biases. They had participants in the study estimate the salaries of men or women in the same profession. Women were consistently estimated to be paid less. Their conclusion:

First, we suggest that the salary estimation effect is not primarily driven by an awareness of the societal phenomenon of the gender gap in wages. Second,we suggest that the operative factor driving the salary estimation effect is a generalized stereotype linking men (more than women) with wealth. Social role theory would hold that this stereotype emerged from repeated observations of men occupying breadwinning roles, holding the highest-earning occupations, and managing household income at a greater frequency than women. Third, we argue that this male wealth stereotype can operate outside of awareness, guiding salary estimates and thus increasing the likelihood that the stereotype can perpetuate real gender salary differences even among the well intentioned.

But even when women do figure out what their work should be worth, the negotiation itself can be a stumbling block.

It's not just that women often aren't trained to assertively negotiate on their own behalf. It's that women who do so may actually be penalized, particularly if the other negotiator is male. As one recent study observed:

Men were significantly more inclined to work with nicer and less demanding women who accepted their compensation offers without comment than they were with those who attempted to negotiate for higher compensation, even though they perceived women who spoke up to be just as competent as women who demurred.

So that's the double bind for women: if you don't ask for a higher salary, you likely won't receive one, but if you do, you may not be hired or promoted.

I doubt there is a simple solution.

But I hope discussion of the gender pay gap isn't pushed aside by Congress as simply a "women's issue". It's always a bit mind-boggling that issues affecting half the population are treated as unimportant or unreasonable. And I hope the family values folks keep in mind that that the pay gap doesn't just affect the half of the population who are women, but any household where a woman's income contributes to household income. The husband is the sole breadwinner in only 18% of married couple families in the U.S. The pay gap is a family issue as well as a fairness issue.